1. Field of the Invention
The present invention relates to a transmission control apparatus for an automobile arranged at or near an instrument panel, and more particularly to a transmission control apparatus allowing absorption of the shock load when the shock load is applied to a control lever of the apparatus.
2. Description of Background Art
In usual, a transmission control apparatus having a shift lever of a manually operated transmission or a selector lever of an automatic transmission (the shift lever and the selector lever will be hereinafter referred to xe2x80x9ccontrol leverxe2x80x9d) is arranged at a center console between a driver""s seat and a assistant driver""s seat. However, it has been proposed to arrange the transmission control apparatus at or near an instrument panel of a vehicle in view of ensuring a wide space on the front floor of vehicle and improving the operability of the transmission control apparatus.
Arrangement of the transmission control apparatus at or near the instrument panel makes it possible to assure a wide space near the front seats and thus to prevent erroneous touch of a driver with the control lever. In addition, since the control lever is positioned adjacent to a steering wheel, it is possible for a driver to quickly move his hand gripping the steering wheel to the control lever.
For example, Japanese Laid-open Patent Publication No. 67245/1998 discloses a technology for absorbing the shock load applied to the control lever of the transmission control apparatus arranged at or near the instrument panel. This technology intends to absorb the shock load with a pivot portion formed on the base end of the control lever being broken when the shock load is applied to the control lever.
Other technologies for absorbing the shock load with the supporting member of the control lever being broken are disclosed in Japanese Laid-open Patent Publication Nos. 129290/1998, 138778/1998 and 278085/1999.
However all of these prior arts intend to absorb shock load only through the breakage of the supporting member of the control lever. Accordingly, although it is possible to absorb the primary shock load, the secondary shock load would be often caused after the control lever having become free.
Japanese Laid-open Patent Publication No. 278085/1999 discloses a transmission control apparatus in which provided are a plurality of means for absorbing shock load through the breakage of the supporting member of the control lever. The shock load is absorbed by this type of shock absorbing means in a discontinuous manner and thus smooth shock absorption cannot be achieved by these shock absorbing means. In addition, since all the shock absorbing steps are performed through the breakage of the supporting member of the control lever, the characteristics of the shock absorption of each shock absorbing means is identical and thus the degree of freedom in setting the shock absorbing characteristics is reduced.
In these prior arts, there is a disclosure of providing a gas layer within a gripping knob for absorbing the shock load. However the gas layer does not act as a cushion when an exceeding shock load is instantaneouly applied to the control knob and thus only the shock absorption through the breakage of the supporting member of the control lever can be achieved, which causes a same problem as that mentioned above.
In addition, it may be conceivable that a supporting member of whole the transmission control apparatus can be broken in order to absorb the shock load when the shock load is applied to the control lever. However this is undesirable in view of reducing a space for the transmission control apparatus since whole the transmission control apparatus including the control lever is displaced in this case and thus it is required to previously keep the space therefor.
It is, therefore, an object of the present invention to provide a transmission control apparatus for an automobile which can improve the space reduction and the degree of freedom in setting the shock absorbing characteristics as well as can smoothly absorb the secondary shock load following the absorption of the primary shock load.
The object of the present invention can be achieved according to the present invention of claim 1 by providing a transmission control apparatus for an automobile to be arranged on or near an instrument panel of a vehicle comprising a bracket for supporting a control lever unit for speed-change operation; a plate secured to the bracket; a shaft passed through both the bracket and the plate for rotatably supporting the control lever unit therearound; a first shock absorbing portion adapted to be broken when a shock load exceeding a predetermined value is applied to the control lever unit in order to absorb the shock load and to release the support of the shaft from the bracket or the plate; and a second shock absorbing portion adapted to be deformed by the shaft released from the bracket and displaced together with the control lever unit over a predetermined stroke in order to continuously absorb the shock load.
According to the structure of claim 1, the applied shock load is firstly absorbed by the breakage of the first shock absorbing portion and secondly continuously absorbed by the deformation of the second shock absorbing portion. It is preferable to provide the first shock absorbing portion on either one of the bracket or the plate and the second shock absorbing portion on the other one of the bracket or the plate.
In the present invention of claim 2, the first shock absorbing portion may comprise a supporting portion forming an aperture through which the shaft is passed; the second shock absorbing portion may comprise a deformable portion formed by a portion through which the shaft can pass and a slot extending along the displacement direction of the shaft and having a width smaller than the outer diameter of the shaft; and the supporting portion and the slot may be formed either in the bracket or in the plate respectively.
According to the structure of claim 2, the primary shock load is firstly absorbed by the breakage of the supporting portion and then the second shock load is continuously absorbed by the deformation of the slots.
In the present invention of claim 3, the supporting portion may be formed in the bracket, and the deformable portion may be formed in the plate.
According to the structure of claim 3, the primary shock load is firstly absorbed by the breakage of the supporting portion formed in the bracket and then the second shock load is continuously absorbed by the deformation of the deformable portion formed in the two plate.
In the present invention of claim 4, a second slot or a notch (recessed portion) may be additionally formed near the slot with extending substantially parallel with the slot.
According to the structure of claim 4, the material forming the second shock absorbing portion may be deformed toward the second slot or the notch.
In the present invention of claim 6, the bracket may be formed by molding, and the first shock absorbing portion (or portions) may be integrally formed with the bracket.
In the present invention of claim 10, the plate may be made of metal having a predetermined ductility.